Download Msys2 from http://www.msys2.org/
Run the installer, it should open the msys2 console when finished, if not run it from the start menu.
Update the package database and core system packages by typing this in the console:
pacman -Syu
Close the console when it tells you to and start it again from the start menu. Choose the 32-bit version.
(we will compile the 32-bit version of KeeperRL, the game works the same regardless if it’s 32 or 64-bit)
Type this in the console:
pacman -Su
Now your Msys2 installation is ready and we can get it to compile KeeperRL.
Start with installing git:

pacman -S git

Now you can download KeeperRL’s source code:

git clone https://github.com/miki151/keeperrl.git

The following commands will install the compiler and necessary libraries:

pacman -S make
pacman -S mingw-w64-i686-gcc
pacman -S mingw-w64-i686-SDL2
pacman -S mingw-w64-i686-SDL2_image
pacman -S mingw-w64-i686-curl
pacman -S mingw-w64-i686-openal
pacman -S mingw-w64-i686-libvorbis

Now you can compile KeeperRL:

cd keeperrl
make -f Makefile-win -j4 DEBUG=true OPT=true RELEASE=true

If the command above doesn’t end with an error (warnings are ok), then KeeperRL should be built. Try running it with:

./keeper.exe